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The present invention relates to belt tensioning, and in particular to a system and method for providing tension to a drive belt in a remotely controlled video surveillance camera.
Maintaining proper tension on drive belts has long been the boon of manufacturers in the security camera industry. Drive belts are used in remotely controlled security cameras to move surveillance cameras in a vertical (tilt) axis and a horizontal (pan) axis to position the cameras as desired by an operator. In order to efficiently transfer drive energy from a drive pulley to an accessory pulley which moves a camera via a drive belt and to be able to accurately position the camera, it is necessary to maintain proper tension of the drive belt therebetween. Prior art systems use complex arrangements of parts to accomplish proper belt tension. Many such systems have numerous components and involve multiple steps by an assembler to adjust properly. For example, some prior art systems use an idler pulley to apply pressure to an exposed portion of the drive belt. By this method, tension on the drive belt is accomplished by pressing against the drive belt to create tension on the idler, drive and driven pulleys. An obvious disadvantage of such a system is the necessity to use an additional friction-bearing pulley within the system. As many drive belt systems have the goal of being operated at maximum duty cycles, it is well known that additional moving parts create additional problems related to wear and tear. Further, the cost of construction of such a device is increased by the number of steps necessary to accomplish the goal of having a properly tensioned drive belt
Alternate methods of maintaining tension on a drive belt include spring loading either the drive pulley or the accessory pulley to apply tension to the belt. Again, problems with this system include the addition of a spring unit which can be susceptible to wear and breakage. Problems attendant to spring-loaded belt tensioning systems include the tendency of the drive pulley to backlash or slip towards the accessory pulley thereby causing inefficient transfer of rotational energy and/or excessive wear and tear.
Still another system of tensioning a belt drive system includes installing either the drive pulley or the accessory pulley on a slotted track whereby either pulley can be moved away from the other to create tension on the drive belt and then set the pulley in place with an attachment means. This method also has attendant disadvantages related to loosening, wear and tear and improper and/or variable tensioning of the belt from unit to unit.
Accordingly, it is desirable to provide a belt drive tensioning system for remotely controlled security cameras to overcome the attendant disadvantages of the prior art systems.
Most remotely controlled cameras are installed in locations such as ceilings, the tops and sides of buildings and other such locations having limited accessibility. Accordingly, it is desirable to provide a reliable system which is not susceptible to the wear and breakage problems present in the prior art.
According to one aspect, the present invention provides a belt drive tensioning apparatus in which a housing has a body wall and a first longitudinal axis. The body wall is configured to position a drive pulley aligned substantially coaxial with the first longitudinal axis. The housing includes a substantially circular tab provided at one end region in which the substantially circular tab has a second longitudinal axis which is parallel and eccentric to the first longitudinal axis.
According to another aspect, the present invention provides a belt drive tensioning system having an accessory pulley. A receptacle has a substantially circular opening and an extension. The extension is disposed partially around a periphery of an end region of the circular opening and projects partially over the opening. A drive pulley is substantially coplanar with the accessory pulley. A housing has a body wall, a first longitudinal axis and a substantially circular tab provided at an end region of the body wall. The substantially circular tab has a second longitudinal axis that is parallel and eccentric to the first longitudinal axis. A drive pulley is substantially coaxially aligned along the first longitudinal axis and is rotatably coupled to the housing. The housing is rotatably transitionable between the first position and a second position within the receptacle so that the substantially circular tab is engaged by the extension when the housing is transitioned to the second position where the drive pulley is at a second distance from the accessory pulley, the second distance being greater than the first distance.
According to still another aspect, the present invention provides a method of tensioning a drive belt for use in a remotely controlled camera system in which a drive pulley is provided adjacent to an accessory pulley. The drive pulley and the accessory pulley are encircled with a drive belt. The drive pulley is moved in an arcuate path away from the accessory pulley to tension the drive belt.